Gen 4 Leak Down Test Results

[Viperless]

I've been wanting to do this for quite a while and finally got around to it yesterday. Wish I would have done it when the car only had 1000 miles on it. Even so, these are the best results of any engine I've ever tested. Curious to hear from other Gen 4 owners who have done this test.

10,000 miles on the odometer. Car has been driven hard. Fresh oil after every other track day.

4% on the dot on all 10 cylinders. I'm thinking that's pretty damn good.

 

[Viper X]

Sounds really good to me.

Oil changes after every other track day being the key.

Dan

 

[Mad Max]

I've done leak down tests on several motors. They all had dampers that had degree marks. On a Viper how do you go about getting each cylinder at TDC?

 

[Viperless]

I've done leak down tests on several motors. They all had dampers that had degree marks. On a Viper how do you go about getting each cylinder at TDC?

By using a high tech device called a long thin wooden stick. I used a 6" wooden q-tip. Stick it in the spark plug hole and feel the piston rise and go past TDC. Back it up a bit to seat the rings and wedge the breaker bar. Then cross your fingers that you got the compression stroke. Smart thing to do would be to follow the firing order.

The best method I ever read, and the one I use all the time, is to go past 10 degrees after TDC then back it up to 10 degrees and lock the crank down. The idea is to have the piston at or near the spot of max cylinder pressure (10-18 degrees after TDC depending on who you believe).

Finding TDC is easy if you have a piston stop. Unless you mark the damper, there's no way to be exact. But you can get close by feel. The key thing is to do it the same way for each cylinder. Go past TDC, back it up a bit, lock the crank down.